Oct. 15, 1874] 



NATURE 



491 



Another powerful reason no doubt is to be found in the difficulty 

 with which even cultivated scientific minds can be brought to 

 recognise, as a truth to be practically acted on, that no science 

 stands alone, that all are intimately connected by nature, and 

 that the classification and separation of various branches of 

 inquiry is an artificial arrangement of man, adopted for tiie more 

 convenient division of labour. 



Tlie time seems to have arrived when we ought to apply this 

 truth to the science of meteorology, and to bring to its aid a 

 class of researches calculated to provide it with that secure and 

 rational basis of which at present it is absolutely destitute. 



Before passing to a consideration of the steps which seem 

 necessary to this end, I will touch slightly on one of the objects 

 the hope to attain which fully justifies their being taken. I 

 allude to the hope that we may thereby find some explanation 

 and some law for the lluctuations of the seasons. 



In a given locality, on a given date, the sun, to whom we 

 ascribe so predondnating an influence, attains, year after year, 

 the same elevation above the horizon, and being at the same dis- 

 tance, presents the same angular area. If the sun, as that date 

 annually recurs, were in all other respects the same, we should 

 have a right to expect an annual recurrence of the same weather, 

 unless some disturbing cause, of which we have at present no 

 knowledge, were known to exist. I do not say positively that 

 the sun being a constant force, we should have this constancy in 

 the seasons — but what I do say is, that if the sun be not a con- 

 stant force, we have no right to expect constancy in the seasons. 

 The first question, therefore, should be : Is the sun a constant 

 force ? Does it, year after year, at the same date, present the 

 same unvaried surface ? We know that the contrary is the case. 



We know that the surface of the sun's disc is never free from 

 spots, and that these spots are constantly changing in number, 

 size, and position : we know that whatever law may govern them, 

 their period of change and return is certainly not annual. 



We know also that the general surface of the sun is covered 

 with markings called facula;, which are perpetually changing, 

 and which have not an annual period. We have also learnt, 

 within two or three years, by the aid of the spectroscope, how at 

 any time to examine the exterior gaseous envelope of the sun, 

 which formerly could only be seen during a total eclipse, and 

 we now know that the famous red prominences of which on 

 those rare occasions we obtained only a fleeting glimpse, on 

 being studied at our ease, without interruption, reveal evidence 

 of activity in those regions of the most stupendous sublimity, 

 darling out, in a few seconds, flames many thousands of miles in 

 extent. Further, in examming the spectrum of the solar light 

 with improved spectroscopes assisted by photography, we find 

 that thousands of lines exist there of which hitherto we had no 

 knowledge — and quite recently ihc researches of Norman Lockyer 

 tend to throw a doubt on the fixity and constancy of some of 

 these lines. 



We have here evidence "which conclusively proves that the 

 sun's surface and sutroundings are not maintained in a constant 

 condition. The evidence may not justify us in asserting that as 

 his surface changes so must the force which he pours out on the 

 earth necessarily change also ; but it certainly Justifies us in 

 entering on a systematic examination of that question with the 

 appliances which modern physical astronomers have contrived 

 for the purpose. 



In what, then, should this systematic study of the sun consist? 

 Up to the present time the spots have been the main object of 

 study. Most valuable observations on these have been made, of 

 which those of Carrington, of Howlett, of Selvvyn, and of the 

 Kew Observatory under the auspices and direction of Warren 

 De la Rue and Balfour Stewart, may be mentioned as the most 

 complete and most long-continued. But excellent as these series 

 are, and great as is their value, this . consists chiefly in their 

 having shown the extent and character of the work that has to 

 be done. They labour under the unavoidable defect of frequent 

 interruption by cloudy weather — about two-thirds of the year are 

 thus lost in England, and the evidence afforded by the remaining 

 one-third is diminished in value. But even some of these re- 

 searches have now been discontinued — in the case of Kew, for 

 want of the requisite funds. 



The conclusion arrived at by those who have devoted them- 

 selves to the subject is that (7 daily record of the changes taking 

 place on the sun's surface is necessary. I will here advert only 

 to the clianges in the spots. These we already know do not 

 take place arbitrarily : they gradually increase in aggregate area 

 to a maximum, and as gradually decrease to a minimum — their 

 period having been provisionally fixed at about 1 1 \ years. But 



this period has been derived from observations of all the spots 

 visible, without discrimination— and the "spotted area" is the 

 aggregate area of all such spots. There is, however, reason to 

 suspect that if it were possible to trace each individual spot 

 throughout its existence, from its first formation to its final dis- 

 appearance, there would be found to be different classes of spots 

 having very different durations and perhaps very different maxi- 

 mum and minimum periods ; and a reduction of these classes 

 separately might, and probably would, result in a considerable 

 modification of of the present il.^ years cycle, and possibly in 

 the discovery of other cycles, at present masked in the period 

 determined irora all spots taken indiscriminately. But hitherto 

 the absence of anything approaching a daily record of the spots 

 has precluded any attempt to classify them. What is true of the 

 spots is also piobably true of all other manifestations of solar 

 energy. 



With respect to sun-spot researches, it fortunately happens 

 that the photographic records need not be all taken at the same 

 station. The record of one day taken in England can be com- 

 bined with the record of the next day taken at the other side of 

 the globe. Hence, in order to obtain this daily record it is only 

 necessary to select a certain number of stations in localities such 

 that there shall always be clear weather at one of them. India 

 offers peculiar facilities for such a selection of stations, owing to 

 the great variety of climate to be found in that country during 

 the same period of the year. Perhaps four or five such stations 

 would suffice for India, and if absolute continuity of record could 

 not be obtained by them, the deficiencies could easily be made 

 good by stations in our colonial possessions. 



I think it hardly necessary that I should state that in advo- 

 cating this system of continuous solar record I do not intend that 

 other methods of meteorological research, now in use, should be 

 abandoned. It is obvious that both methods must be employed. 

 Whether present methods do not admit of considerable extension 

 and improvement,is a very important question,on which, however, 

 I do not here propose to enter. Nor do I intend to discuss the 

 question whether the sun stations now advocated should not also 

 be meteorological stations in the ordinary sense. This, like many 

 other such questions which will have to be settled, is an atlmi- 

 nistrative detail, which I shall not step aside from the considera- 

 tion of fundamental principles to discuss. 



It is scarcely necessary to point out that such a system of daily 

 solar record as I have indicated is beyond the reach of indivi- 

 duals, and must, if attempted at all, be established and main- 

 tained by the State. The degree and direction in which the 

 State should aid the advancement of science has been much 

 debated of late, and the British Association has contributed 

 powerfully, by obtaining a Royal Commission presided over by 

 the Duke of Devonshire, to the solution of this difficult problem. 

 As I have taken a part in these discussions, and have given con- 

 siderable attention to the subject, I may perhaps, without im- 

 propriety, here state what appear to be the principles applicable 

 to the particular case we are now concerned with. 



The first principle is that private enterprise should not only 

 be allowed the most perfect freedom from interference or com- 

 petition by the State, but that it should be encouraged and aided 

 in every possible way. 



The second principle is that the State should step in where 

 private enterprise fails, and itself conduct scientific research, 

 whether observational or experimental, subject to the following 

 main conditions : — 



{a] That the probable results of the research will be beneficial, 

 in the widest sense of that term, to the community at large, or to 

 the various departments of the State. 



(/') That the research is too costly, or commercially too unre- 

 munerative, to be undertaken and vigorously prosecuted by in- 

 dividuals. 



((') That the research requires continuous uninterrupted work 

 extending over very long periods, and conducted by systemati- 

 cally organised establishments. 



Probably no case could be mentioned as so completely satis- 

 fying these three conditions as that of researches affecting closely 

 every interest in the community, needing for their conduct a 

 number of well-equipped establishments, maintained, not 

 merely for many years, but certainly for generations — possibly 

 for centuries. This is work which it is futile to demand from 

 individuals. 



I wish to guard against being thought to assert that the study of 

 the sun will certainly solve all the enigmas of meteorology. I do 

 assert that the strongest possible /W/«ii facie has been made out 

 against the sun as the principal ringleader in meteorological 



